Table 3 Seasonal average concentrations of environmental factors in Suzhou area from 2013 to 2017 (\({\overline{\text{x}}}\) ± s).

Spring

53.7 ± 4.6

83.6 ± 1.0

45.6 ± 4.7

26.0 ± 2.6

108.3 ± 14.0

0.8 ± 0.04

Summer

36.4 ± 5.2

60.4 ± 4.3

32.9 ± 2.5

19.0 ± 0.4

113.0 ± 2.5

0.75 ± 0.01

Autumn

44.1 ± 10.4

73.9 ± 15.8

45.8 ± 8.6

23.2 ± 3.5

85.4 ± 19.6

0.84 ± 0.11

Winter

75.8 ± 11.0

102.7 ± 19.8

53.5 ± 10.1

30.2 ± 5.8

52.6 ± 7.2

1.1 ± 0.12

F value

19.211

13.622

11.578

3.854

28.536

12.801

P value

 < 0.001

 < 0.001

 < 0.001

0.012

 < 0.001

 < 0.001